The invention relates to a yarn breakage position detecting method and a device which can detect a yarn breakage occurrence position when a running yarn is broken in a variety of textile machines and textile manufacturing processes.
In the manufacturing process of a synthetic textile, more specifically, in the manufacturing process of a finished yarn of filaments, there are a spinning stage, a drawing stage, a false twisting stage and other process stages, as is well known. In each of these stages, a variety of processing units, such as guides, rollers, a heater and a false-twisting disc are placed over the entire length of each stage, for example, over an 8 to 10 m long stage, and continuous production is carried out while a yarn is running therethrough. In these stages, breakage of a yarn is usually managed, by a yarn breakage managing device having a yarn breakage detector placed just before the winding portion of each spindle for detecting a yarn breakage, so that the yarn breakage managing device automatically carries out appropriate actions, such as stopping the yarn feeding by the spindle at which a yarn breakage occurs. This prevents troubles, such as a swelling of a roller caused by a broken yarn wound onto the roller, which may induce another yarn breakage in an adjacent spindle.
As mentioned above, however, these stages have many processing members, such as guides, rollers, a heater and a false twisting disc and so on, and each of the processing members may be a cause of an occurrence of yarn breakage. In the case where a yarn breakage frequently occurs due to these processing members, the above mentioned yarn breakage managing device can play its roll if it is only necessary to identify a specific spindle suffering from a frequent yarn breakage within all the spindles. However, a yarn breakage occurs due to many causes, and in the case where the cause of the yarn breakage is to be investigated, a problem arises that there are too many possible causes to promptly analyze them. Therefore, even if countermeasures are taken for respective causes one by one, the yarn breakage problems may not be solved, and lowered productivity is inevitable because this may result in many commercially improper packages due to insufficiency of wound yarn and, in the end, the spindle may be kept stopped until the next periodic maintenance of equipment. With the intensifying demand for cost reduction these days, a solution to this situation is now earnestly sought.
An object of the present invention, in view of the above mentioned situation, is to establish a method and means for clarifying causes of a yarn breakage when the yarn breakage occurs and, thereby, provide a yarn breakage position detecting method and a device capable of immediately clarifying in which stage the yarn breakage occurs.
According to the present invention, there is provided a method of detecting a yarn breakage position where a running yarn is broken in a yarn processing equipment, which comprises the steps of detecting occurrence of yarn breakage by monitoring tension of the running yarn, detecting passage of an end of the broken yarn through a reference position, detecting a period of time from occurrence of the yarn breakage to passage of the yarn end through the reference position, and calculating the yarn breakage position relative to the reference position based on said period of time.
Also, according to the present invention, there is provided a device of detecting a yarn breakage position where a running yarn is broken in a yarn processing equipment, which comprises a tension detector arranged at a reference position and in contact with a running yarn to detect tension of the running yarn, a yarn breakage occurrence detecting means detecting a first time when the yarn is broken by using a tension signal of said tension detector, a yarn end passage detecting means detecting a second time when the broken yarn end passes through the reference position, and a position detecting means detecting the yarn breakage position relative to the reference position based on said first time and said second time.
As is apparent from the above mentioned configuration, in the present invention, the time of occurrence of a yarn breakage is detected and then the time of passage of the broken yarn end is detected at a predetermined reference position. In addition, there is the feature that the position of the yarn breakage relative to the reference position is determined based on the difference between the detected time of occurrence of the yarn breakage and the detected time of passage of the yarn end formed due to the breakage.
Therefore, the yarn breakage position detecting method and the device of the present invention can detect not only whether a yarn breakage occurs, as in the prior art, but also a position where a yarn breakage occurs, which the prior art cannot provide. Therefore, it is possible to immediately identify which processing members cause a yarn breakage in a production stage as mentioned earlier. This means that it is possible to quickly find and fix a specific position or processing member or portion that may frequently cause yarn breakage unless fixed. Therefore, the problem of lowered productivity, mentioned earlier, can be overcome.
Further, because both the occurrence of a yarn breakage and the passage of the yarn end through a reference position are detected by a tension detector, each spindle has only to be provided with a tension detector at its reference position. Accordingly the present invention can be implemented by a very simple configuration with a minimum area of contact with the yarn in the yarn processing region.
As already mentioned, however, a device of the present invention must detect not only occurrence of a yarn breakage but also passage of the broken yarn end based on the tension signal from a tension detector. In view of this point, it is preferable to use a contact type tension detector that detects the tension of a running yarn by keeping a tension detection guide in contact with the yarn. More preferably, the tension detector should be able to reliably retain contact with the running yarn until the passage of the yarn end, and should have a smaller area of contact with the yarn in view of frictional damage and other effects on the yarn.
Such a tension detector is a cantilever tension detector having one contact point, combined with a tension detection guide having a ring- or U-shaped yarn guide to secure the contact with the running yarn. It is also possible to directly apply a well-known commercially available guide detection type tension detector in which a yarn guide and a tension detection guide are placed along the course of the running yarn and the tension of the yarn is detected based on the reactive force from the yarn or on the tension detection guide""s displacement or distortion. This is a preferable application because placing the yarn guide and the tension detection guide along the yarn course allows reliable retention of the yarn until the yarn end passes the reference point.
Further, it is preferable that a tension detector of the present invention is provided with an elastic member, such as a spring, to support the tension detection guide, and its displacement is detected.
This is because the elastic system of the tension detection guide has a natural oscillation waveform and its beginning of appearance in the tension signal can be used to detect the passage of the broken end through a reference position (practically the position of the tension detection guide). This enables reliable detection of the time of passage of the yarn end.
There may also be other yarn breakage position detecting means dedicated for specific processing members and they may be useful if they can properly detect the position of a yarn breakage. However, it is preferable, in view of flexibility and cost, to use the arithmetic approach of the present invention that determines a yarn breakage position, as a yarn length from a reference position to the yarn breakage position, by arithmetically multiplying the speed of the running yarn by the period of time between occurrence of the yarn breakage and passage of the broken yarn end through the reference position.
For accurate detection of a yarn breakage position, it is more preferable to correct the above mentioned yarn length by taking into consideration the elongation of the yarn length by the tension effective before the yarn breakage, and use the corrected yarn length as the yarn breakage position relative to the reference position. If the production stage doesn""t need more than identifying which processing member causes a yarn breakage, however, such highly accurate detection is not required and therefore this correcting system can be omitted.